Treatment of rubber



" Patented Mar. so, 1942 TREATMENT OF RUBBER Ernest Harold Farmer, Radlett, England, assignor v to The British Rubber Producers Research Association, London, England, a body corporate ct (ii-eat Britain No Drawing. Original application October 12,

1938, Serial No. 234,720.

Divided and this application September 7, 1939, Serial No. 293,853. In Great Britain September 22, 1937 6 Claims.

ity of the rubber moleculestowards desirable.

substances such as polyhydric alcohols, amino compounds, hydroxylic substances or vinyl compounds. But although rubber may not react directly with such desirable substances, the effect desired may be attained either by combining the rubber first with reagents or substances which owing to their nature will procure or facilitate combination or the product with the desirable substances in subsequent reactions, or by carrysirable substances in subsequent reactions, or by carrying out the reactions between rubber and the desirable substances in the presence of suitably reactive substances which are capable not only of combining with rubber but in so combining aflord a means of linking the rubber molecules to those of the desirable substances.

In the aforementioned co-pendlng application Serial No. 234,720, reactive derivatives are obtained by combining maleic ydride with rubber conveniently by bringing together the rubber dissolved in a suitable solvent such as toluene, xylene, decalin, cyclohexane or benzene, preferably in dilute solution, with the maleic anhydrlde and a suitable catalyst or condensing agent such as benzoyl' peroxide and maintaining the mixture for a period at a suitable temperature.

The rubber-maleic anhydride products underso change when heated with reagents which might be expected to attack the anhydride groupings incorporated in these substances. For example they react with aniline, caustic alkalies and alcohols when heated with these reagents in a suitable medium. Furthermore the maleic anhydride affords a link whereby the rubber-maleic anhydrlde products may be combined with other substances, for example, polyhydric alcohols such as glycois, amines or amino compounds such as tetramethylene-diamine and hydroxyli'c substances such as cellulose acetate, the products being extracted by precipitation, removal of the solvent, or in other appropriate manner and being in general thermo-plastlmi, resinous, sub stances. V

In the case of vinyl compounds, however. it

' ing out the reactions between rubber and the detion that the two-stage reaction is unsatisfactory but that by simultaneously. reacting by heating together rubber, maleic anhydride and one or other of the members of the group ofvinyl compounds as exemplified by styrene, vinyl acetate and a-methylacrylic ester in. a suitable solvent and in the presence of a smallproportion of benzoyl peroxide to act as condensing agent, there is formed in each case a resinous product which appears to be a homogeneous material formed by union of rubber, maleic anhydride and the vinyl compound, and which differs in characteristics and yield from the products obtained by heating together in a suitable medium and in presence of a small proportion of benzoyl peroxide (a) rubber and maleic anhydride, and (b) maleic anhydride and the vinyl compound.

The following examples will serve to illustrate the invention.

' Example 1 product is an apparently homogeneous resin apparently composed of rubber, maleic anhydride and styrene, weighing 16 gr,

The yield of the final product improves considerably when an increased proportion of benzoyl peroxide is used. Thus when the experiment is repeated using in turn 0.3 gram," 0.5

, gram, 1.0 gram of benzoyl peroxide, the yields of resin are respectively 26.2 grams, 28.6 grams and 28.3 grams.

When the proportions of the reactants are somewhat varied, using rubber 10 .grams), maleic anhydrideilO grams), styrene (10 grams) and benzoyl peroxide (0.! gram), all in toluene (410 grams), a resinous product weighing 30 grams is finally obtained.

- All the foregoing products resembled in superficial appearance the rubber-maleic anhydride products described in the aforementioned appllcation, but differed materially in their nature :lrom, and were obtained in superior yield to,

the resins which may be obtained by heatingto sether maleic anhydride and styrene in a suitable solvent (e. g., toluene, carbon tetrachloride or xylene) with a littlebenzoyl peroxide as. conhas been found according to the present inven-ts (lensing agent.

, Example 2 A solution of rubber (10 grains) in xylene (410 grams) is mixed with maleic anhydride (10 grams), vinyl acetate (10 grams) and benzoyl peroxide (0.7 gram, dissolved in alittle xylene):

poured withstirring into alcohol gives a precipitate, which after being washed with alcohol and dried in vacuo constitutes a homogeneous resin. Yield 15.2 grams.

As mentioned in co-pending application Serial No. 234,720 previously referred to, increase in the proportion of maleic anhydride employed in relation to the rubber enhances the degree of reactivity of the individual rubbermolecules, the limit of such reactivity being apparently reached when each C5Ha unit of the rubber combines with one molecule of maleic anhydride (3411203.

What I claim is:

1. A process for the preparation of modified rubber derivatives or resins consisting in reacting maleic anhydride with rubber and a compound selected from the group consisting of styrene, vinyl acetate and a-methacrylic ester in solution in the presence of a catalyst or condensing agent and maintaining the mixture at a temperature of 70 to lOO" C. for a period of several hours.

2. A process for the preparation of modified rubber derivatives or resins according to claim 1,

- wherein the reaction is carried out in the presence of a peroxide catalyst or condensing agent.

3. A process for. the preparationof modified rubber derivatives or resins according to claim 1, wherein the reaction is eflected with the rubber,

mmaleic anhydrideand compound selected from the group consisting of styrene, vinyl acetate and a-methacrylicester in solution in toluene or xylene.

4. A process for the'preparation of modified rubber derivatives or resins according to claim 1, wherein the reaction product is extracted with alcohol.

5. A process for the preparation of modified rubber derivatives or resins, consisting in mixing a solution of rubber in toluene with styrene, maleic anhydride and a small proportion 0! ben-. zoyl peroxide, maintaining the mixture at a temperature of about 85 C. and precipitating the reaction product with alcohol.

6. A process for the preparation of modified rubber derivatives or resins, consisting in mixing ERNEST HAROLD FARMER. 

